Oxidative treatment of hair with reduced hair damage

ABSTRACT

The present invention relates to hair care compositions comprising chelants and methods for reducing oxidative hair damage. The compositions contribute to reducing the oxidative damage sustained by keratinous fibers such as human hair during bleaching, dyeing, perming or other oxidative treatments. The compositions according to the present invention also provide excellent color evenness and color fastness.

CROSS REFERENCE TO RELATED APPLICATION

The application is a continuation of International applicationPCT/US02/08482 (Case CM2517M2) filed on Mar. 19, 2002.

FIELD

The present invention relates to hair care compositions comprisingchelants and methods for reducing oxidative hair damage during oxidativetreatments of hair such as bleaching, oxidative dyeing or perming.

BACKGROUND

Melanin is a natural pigment found in hair. Melanin and hair-formingcells are naturally produced in the hair bulb at the root of the hair.As new cells are produced, the older ones are pushed upwards out of theskin to form the hair shaft, which is the part of the hair that can beseen above the scalp. Hair can be schematically described as being madeof a center part called the cortex, which contains the melanin, and anouter layer called the cuticle. It is the cortex that gives hair itsspecial qualities such as elasticity and curl.

The hair shaft is made of dead cells that have turned into a mixture ofdifferent forms of the special hair protein, keratin. Keratin containshigh concentrations of a particular amino acid called cystine. Everycystine unit contains two cysteine amino acids in different chains,which have come to lie near each other and are linked together by twosulphur atoms, forming a very strong chemical bond known as a disulphidelinkage. This cross-linking by disulphide linkages between the keratinchains accounts for much of the strength of the hair.

Bleaching and dyeing (or coloring) of hair has become increasinglypopular over the past years. Younger people may want to change thenatural color of their hair to a more fashionable one, while olderpeople may also use dyeing compositions to conceal gray hair. As peoplegrow older, the production of melanin slows, giving more and more grayhair over time. Melanin can be purposely altered by chemical treatmentsto give lighter shades. The lightening is achieved by oxidizing themelanin pigments, usually with an oxidizing agent in alkaline solution,also called bleaches. Examples of oxidizing agents that can be used arehydrogen peroxide, potassium, sodium or ammonium salts of perborate orpercarbonate, persulfate and percarbamide.

Bleaches are also used during oxidative dyeing treatments. Oxidative (or“permanent”) dye compositions comprise “precursor dyes” which are smallmolecules capable of diffusing into the hair. These molecules mainlybelong to three classes of aromatic compounds: diamines, aminophenolsand phenols. They are sufficiently small to diffuse in the hair shaftwhere, once activated by an oxidizing agent such as hydrogen peroxide,they further react with other precursors to form larger coloredcomplexes. Oxidative hair dye compositions commonly contain, in additionto the dye precursors and a source of peroxide, a variety of additionalcosmetic and peroxide stabilizing agents.

Oxidizing agents can activate oxidative dye precursors across a range ofpH. However, it is known that enhanced dye oxidation can be achieved viathe use of a hair-swelling agent (HSA) that can adjust the pH of theoxidizing solution. Such HSA's further enhance the oxidizing and dyeingprocess by swelling the hair fibers to aid both the diffusion of theperoxide and dyeing agents into the hair and enabling faster, morethorough dye oxidization and hair dyeing. Preferred hair-swelling agentsfor adjusting the pH of peroxide hair oxidizing compositions are aqueousalkaline solutions containing ammonia (ammonium hydroxide) ormonoethanolamine(MEA).

Low levels of chelants are routinely used as stabilizers orpreservatives in various oxidizing compositions. For example, EDTA(ethylenediaminetetraacetic acid) is commonly used as a stabilizer inhydrogen peroxide solution, which would otherwise decompose too rapidlyand could not be stored for a long time. Ethylene diaminedissucinnicacid (EDDS) is also known as a good stabilizing agent component toincrease the stability of laundry bleaching products. Amounts as low as0.1% by weight of the oxidizing composition are usually used tostabilize the oxidizing agent contained in said oxidizing compositions.

Oxidative treatments of hair such as bleaching (decoloration) andoxidative dyeing give good results and are very commonly used. They arehowever not without drawbacks. The oxidizing agents used for bleachingand oxidative dyeing damage hair to some extent. The mechanism by whichdamage is caused to the hair fibers is not perfectly understood.However, it is known that some of the disulphide bonds linking thekeratin chains break in the presence of oxidizing compositions. Repeatedoxidative treatments leave weak, brittle hairs, which have little shineand luster. An enormous effort has been made to address this problemover the past years, and various solutions have been proposed.

Today, most dyeing or bleaching compositions are sold with aconditioner, which is applied on hair after the bleaching or dyeingcomposition has been rinsed off. Examples of conditioning agents aresilicones, cationic surfactants and cationic polymers. Howeverefficient, conditioners cannot prevent successive chemical treatmentscausing premature hair breakage. In fact, conditioners do not bring thehair back to its initial condition but merely conceal the damage under aprotective layer of the conditioning agent, which only results in animproved feel of the hair.

Attempts have been made to protect the hair from damage instead ofmerely concealing it. U.S. Pat. No. 5,100,436 discloses hair dyeingcompositions comprising metal-chelant complexes. The use of catalyticamounts of dipyridyl or o-phenanthroline complexes (0.001 to 0.1% byweight of the solution) allows a reduction in the time of exposure, thusreducing the damage caused by the oxidizing agent.

U.S. Pat. No. 6,013,250 discloses composition for treating hair againstchemical and photo damage by the use of hydrolyzed proteins having anabundance of anionic amino acids and in particular, sulphur-containingamino acids. These proteins serve as “decoys”, in order to minimize thedamage caused to the natural disulphide bonds.

U.S. Pat. No. 4,138,478 discloses agents for reducing the damage to hairduring bleaching and dyeing by the use of a water-soluble3-amino-1-hydroxypropane-1,1-diphosphonic compound for protecting hairfrom damage by “nascent oxygen”. According to this patent, “thediphosphonic compound is substantively adsorbed by the hair and acts tohinder degradation of the hair by nascent oxygen which is either presenttherewith or which is substantially added”. Other protective compoundssuch as hydroxyethane-1,1 diphosphonic acid (HEDP) andethylenediaminetetramethylene phosphonic acid (EDTMP) are disclosed atlow levels in U.S. Pat. No. 3,202,579 and U.S. Pat. No. 3,542,918.

“Properties of peroxide-bleached hair” (W. Edman & E. Marti, J. Soc.Cosmet. Chem., 1960, p. 133), discloses that an aqueous solution ofhydrogen peroxide is stabilized by adding 0.1% by weight of thebleaching composition of tetrasodium salt of EDTA (ethylenediaminetetraacetic acid) and that damage to hair can be prevented by adding0.1% of the tetrasodium salt of EDTA to the aqueous bleachingcompositions. However, is has now been surprisingly found that EDTA,although widely used in bleaching and dyeing compositions, displays verylittle benefits, unless utilized at levels much higher than 0.1%.

Chelants in hair care compositions have been used to remove mineralsbound to hair. For example, U.S. Pat. No. 5,635,167 discloses a processfor the removal of exogenous metal ions that have become attached tohair. The treatment comprises a step wherein hair is contacted with ablend of chelating agents (selected from the group consisting of aminoacid chelating agents, polyphosphate chelating agents and phosphonatechelating agents) at a pH of between 4 and 9 and at a concentration ofbetween 4% to 25% by weight.

WO97/24106, Dias et al. discloses hair coloring compositions comprisinga water soluble peroxygen-bleach, a bleaching aid selected from organicperoxyacid bleach precursors and preformed organic peroxyacids and oneor more hair coloring agents. Various chelants are disclosed as optionalingredients and exemplified in hair care compositions at 0.1% by weightof the composition. The organic peroxy acid bleach precursors aredefined as organic compounds that react with hydrogen peroxide in aperhydrolysis reaction to produce a peroxyacid. These bleaching aids areclaimed to provide benefits including reduced hair damage at lower pH.However, the Applicant has found that at a pH higher than 8, thesebleaching aids are much more damaging to hair than usual water-solubleoxidizing agents such as hydrogen peroxide. Without being bound bytheory, the Applicant believes that the conjugate base of the organicperoxyacid formed at a pH above 8 is more likely to oxidize thedisulphur bonds of the keratin than other oxidizing agents such ashydrogen peroxide. Additionally, hair coloration, especially withoxidative dyes is much poorer at pH 8 than pH 10, which is anotheradvantage of this invention over WO9724106. Finally peroxyacidprecursors are difficult to solubilize, especially in oil-in-wateremulsion.

Despite these developments, damage to hair caused by the stronglyaggressive chemicals contained in most bleaching, dyeing or permingcompositions particularly with repeated usage is still a problem,particularly at high pH.

It is hence an object of the present invention to provide newcompositions capable of improved protection of keratinous fibers such ashuman hair from oxidative damage, in particular the structurallyimportant keratin bonds such as the disulphide bonds from oxidativebreakage.

It is another object of this invention to provide bleaching, dyeing orperming compositions with a better efficiency in terms of light shade,color evenness, color fading and hair feel.

It is another object of this invention to provide bleaching or dyeingcompositions capable of protecting keratinous fibers such as hair whileat the same time delivering a good lightening effect.

It is another object of the present invention to provide methods oftreating hair with chelants for reducing oxidative hair damage.

It has now been surprisingly found that chelants have excellent damageinhibiting properties. None of the above-mentioned references disclosethe compositions of the present invention.

SUMMARY

The subject of the present invention is a composition suitable for useduring a hair treatment comprising:

-   a) an oxidizing agent;-   b) a chelant;    wherein said chelant is in an amount sufficient to provide a damage    benefit equivalent to less than 160, preferably less than 140, more    preferably less than 120, even more preferably less than 110 cysteic    acid units as measured by the FT-IR Damage Assessing Protocol after    a 5-Cycle Oxidative Hair Treatment Protocol With 2 Intermediate    Washes as defined herein and/or to provide a damage benefit    equivalent to a Normalized Shine Ratio of at least 0.80, preferably    at least 0.85, more preferably at least 0.95, even more preferably    at least 0.99 as measured by the Goniophotometer Damage Assessing    Protocol after a 5-Cycle Hair Oxidative Treatment Protocol With 10    Intermediate Washes as described herein.

DETAILED DESCRIPTION

While the specification concludes with claims which particularly pointout and distinctly claim the invention, it is believed the presentinvention will be better understood from the following description.

As used herein the term “hair” to be treated may be “living” i.e. on aliving body or may be “non-living” i.e. in a wig, hairpiece or otheraggregation of non-living keratinous fibers. Mammalian, preferably humanhair is preferred. However wool, fur and other keratin containing fibersare suitable substrates for the compositions according to the presentinvention.

As used herein, the term “oxidizing composition” means a compositioncomprising at least one oxidizing agent suitable for use on hair, suchas hydrogen peroxide, sodium, potassium, ammonium or other salts ofperborate, percarbonate, persulfate and percarbamide. Examples of suchcompositions are oxidative dye compositions and bleaching compositions.

As used herein the term “oxidative treatment of hair” or a “hairtreatment comprising at least one oxidative step” is used in the broadsense in that it is intended to encompass all treatments of haircomprising at least one step of contacting hair with at least oneoxidizing composition. Examples of oxidative treatment for human hairare bleaching, dyeing or perming.

As used herein the term “immediately” means within about 1 hour,preferably within about 30 mn, more preferably within about 15 mn.

As used herein the term “log x” refers to the common (or decimal)logarithm of x.

All percentages are by weight of the total composition unlessspecifically stated otherwise. When more than one composition are usedduring a treatment, the total weight to be considered is the totalweight of all the compositions applied on hair simultaneously (i.e. theweight found “on head”) unless otherwise specified. All ratios areweight ratios unless specifically stated otherwise.

All cited references are incorporated herein by reference in theirentireties. Citation of any reference is not an admission regarding anydetermination as to its availability as prior art to the claimedinvention.

Chelants

Definition

The term “chelant” (or “chelating agent” or “sequestering agent”) iswell known in the art and refers to a molecule or a mixture of differentmolecules each capable of forming a chelate with a metal ion. A chelateis an inorganic complex in which a compound (chelant) is coordinated toa metal ion at two or more points so that there is a ring of atomsincluding the metals. Chelants contain two or more electron donor atomsthat form the coordination bonds with the metal ion.

Chelants are well known in the art and a non-exhaustive list thereof canbe found in A E Martell & R M Smith, Critical Stability Constants, Vol.1, Plenum Press, New York & London (1974) and A E Martell & R D Hancock,Metal Complexes in Aqueous Solution, Plenum Press, New York & London(1996) both incorporated herein by reference.

When related to chelants, the terms “salts and derivatives thereof” meanall salts and derivatives comprising the same functional structure asthe chelant they are referring to and that have similar or betterchelating properties. These terms include alkali metal, alkaline earth,ammonium, substituted ammonium salts (e.g monoethanolammonium,diethanolammonium, triethanolammonium), esters of chelants having anacidic moeity and mixtures thereof, in particular all sodium, potassiumor ammonium salts. The term “Derivatives” also includes “chelatingsurfactant” compounds (these are chelants modified to bear a surfactantmoiety while keeping the same chelating functionality, see U.S. Pat. No.5,284,972, “N-acyl-N,N′,N′-ethylenediaminetriacetic acid” for an exampleof modified ethylenediaminetriacetic acid). The term “Derivatives” alsoincludes large molecules comprising one or more chelating groups havingthe same functional structure as the parent chelants. Examples of theselarge molecules is polymeric EDDS (ethylenediaminedisuccinic acid) madeof unit block according to the following structure:

and disclosed in U.S. Pat. No. 5,747,440 Kellett et al.

Preferred chelants for use herein are carboxylic acids (in particularaminocarboxylic acids), phosphonic acids (in particular aminophosphonicacids) and polyphosphoric acids (in particular linear polyphosphoricacids), their salts and derivatives.

Aminocarboxylic Acid Chelants

Carboxylic acid chelants as defined herein are chelants having at leastone carboxylic acid moiety (—COOH).

Examples of aminocarboxylic acid chelants suitable for use hereininclude nitrilotriacetic acid and polyaminocarboxylic acids such asdiethylenetriamine pentaacetic acid (DTPA), ethylenediamine disuccinicacid (EDDS), ethylenediamine diglutaric acid (EDGA),2-hydroxypropylenediamine disuccinic acid (HPDS),glycinamide-N,N′-disuccinic acid (GADS), ethylenediamine-N-N′-diglutaricacid (EDDG), 2-hydroxypropylenediamine-N-N′-disuccinic acid (HPDDS),ethylenediaminetetraacetic acid (EDTA), salts thereof and derivativesthereof.

Other suitable aminocarboxylic chelants for use herein are iminodiaceticacid derivatives such as N-2-hydroxyethyl N,N diacetic acid or glycerylimino diacetic acid (described in EP-A-317,542 and EP-A-399,133),iminodiacetic acid-N-2-hydroxypropyl sulfonic acid and aspartic acidN-carboxymethyl N-2-hydroxypropyl-3-sulfonic acid (described inEP-A-516,102), β-alanine-N,N′-diacetic acid, aspartic acid-N,N′-diaceticacid, aspartic acid-N-monoacetic acid and iminodisuccinic acid chelants(described in EP-A-509,382), ethanoldiglycine acid, salts thereof andderivatives thereof.

EP-A-476,257 describes suitable amino based chelants. EP-A-510,331describes suitable chelants derived from collagen, keratin or casein.EP-A-528,859 describes a suitable alkyl iminodiacetic acid chelants.Dipicolinic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid are alsosuitable.

Preferred aminocarboxylic chelants are diamine-N,N′-dipolyacid andmonoamine monoamide-N,N′-dipolyacid chelants, salts thereof andderivatives thereof. Preferred polyacids contain at least two acidgroups independently selected from the carboxylic acid group (—COOH),sulphonic group (—SO₃H), the o-hydroxyphenyl group, the m-hydroxyphenylgroup and the p-hydroxyphenyl group. Suitable polyacids include diacids,triacids and tetraacids, preferably diacids. Preferred salts includealkali metal, alkaline earth, ammonium or substituted ammonium salts.EDTA is a tetramonoacid and does not belong to this class of preferredchelants.

Preferably, the polyacids are di-carboxylic acids, preferablydi-carboxylic acids having a carbon chain length of from about 3 toabout 10 carbon atoms, more preferably from about 4 to about 6 carbonatoms, even more preferably about 4 carbon atoms.

Exemplary diamine dipolyacids suitable for use herein includeethylenediamine-N,N′-disuccinic acid (EDDS),ethylenediamine-N,N′-diglutaric acid (EDDG),2-hydroxypropylenediamine-N,N′-disuccinic acid (HPDDS), all disclosed inEuropean Patent EP0687292, ethylenedicysteic acid (EDC) disclosed inU.S. Pat. No. 5,693,854, diaminoalkyldi(sulfosuccinic acids) (DDS)disclosed in U.S. Pat. No. 5,472,642 and EDDHA(ethylenediamine-N-N′-bis(ortho-hydroxyphenyl acetic acid)), a method ofpreparation of which is disclosed in EP331556. A preferred monoaminemonoamide-N,N′-dipolyacid is glycinamide-N,N′-disuccinic acid (GADS),described in U.S. Pat. No. 4,983,315.

Highly preferred for use herein is ethylenediamine-N,N′-disuccinic acid(EDDS), derivatives and salts thereof. Preferred EDDS compounds for useherein are the free acid form, and salts thereof. Preferred saltsinclude alkali metal, alkaline earth metals, ammonium and substitutedammonium salts (e.g. monoethanolammonium, diethanolammonium,triethanolammonium). Highly preferred salts are sodium, potassium,magnesium and calcium salts. Examples of such preferred sodium salts ofEDDS include Na₂EDDS and Na₃EDDS.

The structure of the acid form of EDDS is as follows:

EDDS can be synthesised, for example, from readily available,inexpensive starting materials such as maleic anhydride andethylenediamine. The synthesis of EDDS from maleic anhydride andethylene diamine yields a mixture of three optical isomers, [R,R],[S,S], and [S,R] (25% S,S, 50% R,S and 25% R,R), due to the twoasymmetric carbon atoms. The biodegradation of EDDS is opticalisomer-specific, with the [S,S] isomer degrading most rapidly andextensively.

U.S. Pat. No. 5,747,440, Kellett et al., discloses EDDS derivativescomprising an modified polyamine having units of the formula:

Preferred aminocarboxylic acid chelants that are notdiamine-N,N′-dipolyacid and monoamine monoamide-N,N′-dipolyacid chelantsinclude N,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid(HBED) salts thereof and derivatives thereof:

Examples of suitable HBED derivatives can be found in WO9744313.Polyphosphoric Acid Chelants

Suitable polyphosphoric acid type chelants include molecules thatcontain more than one P atom and have P—O—P bonds. Polyphosphoric acidchelants and salts (polyphosphates) can be linear and are generallyrepresented by the formula [P_(n)O_(3n+1)]^((n+2)−)M_((n+2))⁺ wherein Mis a suitable counter-ion such as H⁺, Na⁺ or K⁺ and n an integer.Polyphosphoric acid type chelants and their polyphosphate salts can alsobe cyclic and have the formula [P_(n)O_(3n)]^(n−)M_(n) ⁺. Representativeexamples include, among other, sodium tripolyphosphate, tetrasodiumdiphosphates, hexametaphosphoric acid and sodium metaphosphate.

Phosphonic Acid Chelants

Suitable phosphonic acid type chelants include amino alkylene poly(alkylene phosphonic acid), ethane 1-hydroxy diphosphonic acids andnitrilo trimethylene phosphonic acids, salts thereof and derivativesthereof. Suitable chelants of this type are disclosed in U.S. Pat. No.4,138,478, Reese et al., U.S. Pat. No. 3,202,579 and U.S. Pat. No.3,542,918, Berth et al, all incorporated herein by reference.

Preferred phosphonic acid type chelants for use herein have the formula(I) below:

wherein each X are independently selected from hydrogen or alkylradicals, preferably hydrogen or alkyl radicals having from 1 to 4carbon atoms, preferably hydrogen; and each R₁ are independentlyselected from —PO₃H₂ or a group having the formula (II) below:

Preferred chelants according to Formula (I) for use herein areaminotri-(1-ethylphosphonic acid),ethylenediaminetetra-(1-ethylphosphonic acid),aminotri-(1-propylphosphonic acid), aminotri-(isopropylphosphonic acid)and chelants having the formula (III) below:

wherein each R₂ are independently selected from —PO₃H₂ or a group havingthe formula (IV) below:

Especially preferred chelants according to formula (III) for use hereinare aminotri-(methylenephosphonic acid),ethylene-diamine-tetra-(methylenephosphonic acid) (EDTMP) anddiethylene-triamine-penta-(methylenephosphonic acid) (DTPMP).

Examples of Other Chelants:

Examples of other chelants suitable for use herein include but are notlimited to polyethyleneimines as disclosed in U.S. Pat. No. 5,955,415.

Levels

Chelants must be present in the composition at a level sufficient toprovide a benefit measurable by the FT-IR Damage Assessing Protocolafter a 5-Cycle Oxidative Hair Treatment Protocol With 2 IntermediateWashes and/or by the Goniophotometer Damage Assessing Protocol after a5-Cycle Hair Oxidative Treatment Protocol With 10 Intermediate Washes,both of which are defined herein.

Levels of chelants in the oxidizing compositions or in pre-treatcompositions can be as low as about 0.25%, preferably at least about0.5% for the most effective chelants such as diamine-N,N′-dipolyacid andmonoamine monoamide-N,N′-dipolyacid chelants (for example EDDS). Lesseffective chelants will be more preferably used at levels of at leastabout 1%, even more preferably above about 2% by weight of thecomposition, depending of the efficiency of the chelant. Levels as highas about 10% can be used, but above this level significant formulationand/or human safety issues arise. Levels above about 4% can be used butwill usually not result in additional damage benefit.

Damage Prevention

The Applicant has surprisingly found that chelants could efficientlyprevent oxidative hair damage when formulated in level higher thanpreviously mentioned in the literature or formulated in commercialcompositions. Levels of chelants used in the prior art are, at best, toolow to be really useful and sometimes totally inefficient (SeeExperimentals). This is particularly true for formulations withrheologies greater than water such as oil-in-water emulsions orthickened aqueous solutions.

Oxidative hair damage can be measured by the FT-IR Damage AssessingProtocol and/or by the Goniophotometer Damage Assessing Protocol, bothdescribed below.

It is was found that it is highly relevant for the consumer thatoxidizing compositions comprise a chelant or a mixture of chelants in anamount sufficient to provide a damage benefit equivalent to:

a) less than 160, preferably less than 140, more preferably less than120, even more preferably less than 110 cysteic acid units as measuredby the FT-IR Damage Assessing Protocol after a 5-Cycle Oxidative HairTreatment Protocol as defined below; and/or

b) a Normalized Shine Ratio of at least 0.80, preferably at least 0.85,more preferably at least 0.95, even more preferably at least 0.99 asmeasured by the Goniophotometer Damage Assessing Protocol after a9-Cycle Hair Oxidative Treatment Protocol as described herein.

Conditional Stability Constants of Preferred Chelants

Good results such as those described above can be achieved by increasingthe levels of previously used chelants or by using level of selectchelants that were found to be particularly efficient even at lowlevels. These particularly efficient chelants have a much strongeraffinity for transition metal ions such as Cu²⁺ than for alkaline-earthmetal ions such as Ca²⁺ at pH 10. One relatively easy way of predictinghow well a chelant will perform is calculating the ratio of the log ofthe Conditional Stability Constant of the chelant for Cu²⁺ to the log ofthe Conditional Stability Constant of the chelant for Ca²⁺ at pH 10 asdescribed below.

The Conditional Stability Constant is a parameter commonly used in theart to practically assess the stability of metal-chelant complex at agiven pH. A detailed discussion on Conditional Stability Constant can befound for example in “Dow chelating agents” published by the DowChemical Company Limited, incorporated herein by reference.The Stability constant of a metal chelant interaction can be defined as:$K_{ML} = \frac{\lbrack{ML}\rbrack}{\lbrack M\rbrack\lbrack L\rbrack}$

Where:

[ML]=Concentration of metal chelant complex at equilibrium

[M]=Concentration of free metal ion

[L]=Concentration of free chelant

K_(ML)=Stability constant for the metal chelant complex

Wherein all concentrations are expressed in mol/dm³. Stability constantsare conveniently expressed as logarithms. The values of the logarithmsof the Stability constant values for some exemplary metal ion—chelantcomplexes are given in the following table:

Table 1—Log Stability constants for 1:1 complexes of various chelantswith Cu and Ca [I] (fully deprotonated chelants) log K* Agent Cu Ca EDDS18.35 4.58 DTPMP 19.5 7.1 EDTMP 23.2 9.36 DTPA 21.4 10.75 HEDP 11.84 6.0EDTA 18.78 10.65 EDDHA 25.3 7.2*All measured at 25deg and 0.1M ionic strengthMost chelants have a degree of protonation that is dependent on pH. Thiscan be expressed using chelant proton Stability constants (stepwise K).These Stability constants are obtained from the equation below:$\begin{matrix}\left. {H + {LHn}}\rightleftharpoons{LH}_{n + 1} \right. & {K_{{Hn} + 1} = \frac{\left\lbrack {LH}_{n + 1} \right\rbrack}{\lbrack H\rbrack\left\lbrack {LH}_{n} \right\rbrack}}\end{matrix}$

The values of the proton chelant Stability constant for some usualchelants are given in the tables below: TABLE 2a log protonationconstants for tetra-protonated chelants [1] HL³⁻ H₂L²⁻ H₃L⁻ H₄L EDDS⁴⁻10.01 6.84 3.86 2.95 HEDP⁴⁻ 10.8 6.88 2.53 1.8 EDTA⁴⁻ 10.19 6.13 2.692.00 EDDHA⁴⁻ 12.1 9.5 8.5 6.3

TABLE 2b log protonation constants for penta-protonated chelants [1]HL⁴⁻ H₂L³⁻ H₃L²⁻ H₄L⁻ H₅L DTPA⁵⁻ 10.48 8.60 4.28 2.6 2.0

TABLE 2c log protonation constants for hepta-protonated chelants [1]HL⁶⁻ H₂L⁵⁻ H₃L⁴⁻ H₄L³⁻ H₅L²⁻ H₆L⁻ H₇L EDTMP⁷⁻ 13.0 9.78 7.94 6.42 5.173.02 1.30

TABLE 2d log protonation constants for octa-protonated chelants [1] HL⁷⁻H₂L⁶⁻ H₃L⁵⁻ H₄L⁴⁻ H₅L³⁻ H₆L²⁻ H₇L⁻ H₈L DTPMP⁸⁻ 12.0 10.10 8.15 7.17 6.385.50 4.45 2.8[1] = Arthur Martell & Robert M Smith, Critically Selected StabilityConstants of Metal Complexes Database, Version 3.0

The stability constants of chelant-metal ion complexes are welldocumented in the literature for commonly used chelants (see forexample=Arthur Martell & Robert M Smith, Critically Selected StabilityConstants of Metal Complexes Database, Version 3.0 and above,incorporated herein by reference). When not documented the constants canstill be measured using various analytical methods (see “Metal Complexesin Aqueous Solutions”, Martel and Hancock, edition Modem InorganicChemistry, p. 226-228, incorporated herein by reference).

The gradual change in chelant species as pH changes can be representedusing alpha coefficients (α_(HL)), defined as${{Alpha}\quad{{coefficient}\left( {{at}\quad a\quad{given}\quad{pH}} \right)}} = \frac{{Total}\quad{concentration}\quad{of}\quad{ligand}}{{Free}\quad{ligand}\quad{concentration}}$In the case of tetra-acid chelants the values can be calculated fromα_(HL)=1+K ₁ [H]+K ₁ K ₂ [H] ² +K ₁ K ₂ K ₃ [H] ³ +K ₁ K ₂ K ₃ K ₄ [H] ⁴

A further factor affecting metal chelant interactions is the tendency ofmetals to form hydroxide species as the pH increases. This effect can berepresented using metal alpha values [2] as summarised in the tablebelow at pH 10: TABLE 3 log alpha values for metal ions [2] pH Ca²⁺ Cu²⁺10 0.0 2.00

[2]=A Ringbom & E Wanninen, Treatise on Analytical Chemistry, 2nd Ed,1979, Part 1, Vol 2

By combining Stability constants and alpha constants at pH 10 we can usethe formula below to give the effective chelating power of a chelant.This is the Conditional Stability Constant referred to in this PatentApplication. ${\begin{matrix}{{K_{ML}({cond})} = \frac{K_{ML}}{\alpha_{M} \cdot \alpha_{HL}}} & {{\log\quad{K_{ML}({cond})}} =}\end{matrix}\log\quad K_{ML}} - {\log\quad\alpha_{HL}} - {\log\quad\alpha_{M}}$

The data for a range of chelants with Cu and Ca is given below: logConditional Stability Constant (pH 10) Chelant Cu Ca Ratio Cu/Ca EDDHA21.04 4.97 4.23 EDDS 16.04 4.27 3.76 DTPMP 15.14 4.74 3.19 EDTMP 17.996.15 2.92 DTPA 18.78 10.13 1.85 HEDP 8.98 5.13 1.75 EDTA 16.37 10.241.60

The applicant has surprisingly found that levels as low as 0.25% byweight of chelants having a ratio$\frac{\log\quad K_{CuL}}{\log\quad K_{CaL}}$(wherein log K_(CuL) is the common logarithm of the ConditionalStability Constant between this chelant and Cu²⁺ and wherein log K_(CaL)is the common logarithm of the Conditional Stability Constant betweenthis chelant and Ca²⁺, both at pH 10) of at least 3.20 give goodoxidative damage protection. This$\frac{\log\quad K_{CuL}}{\log\quad K_{CaL}}$ratio should preferably be at least 3.30, more preferably at least 3.40,even more preferably at least 3.50 at pH 10. It is important tocalculate this ratio at pH 10 because oxidizing compositions fortreating hair usually have a pH of from 8 to 12. Using stabilityconstants without taking into account the influence of the pH is acommon mistake and will give misleading results for the purpose ofidentifying chelants that will prevent oxidative damage at low levels.Hydrogen Peroxide Decomposition Ratio (% Loss)

It is preferred that the complexes formed by these preferred chelantsefficiently inhibit the red-ox chemistry of Cu²⁺. The ability ofchelants to inhibit the red-ox chemistry of the chelated copper metalion can be effectively compared using their Hydrogen PeroxideDecomposition Ratio (% Loss) as measured by the Hydrogen PeroxideDecomposition Ratio Measurement Protocol described hereafter in the“EXPERIMENTALS” section.

The table below shows the Hydrogen Peroxide Decomposition Ratio (% Loss)for different chelants: Chelant Peroxide % at t = 0 Peroxide % at t =30mn % Loss EDTA 3.576 3.573 0.1% EDDS 3.150 3.104 1.5% DTPMP 3.0782.964 3.7% MGDA 3.498 3.104 11.3%  HEDP 4.126 2.792 32.3%  No chelant0.563 —  100% 

MGDA is methylglycinediacetic acid and forms a pentadentate complex withCu²⁺.

Chelants forming hexadentate type complexes with Cu²⁺ were found toadequately inhibit the red-ox chemistry of the metal ion (“hexadendatecomplex” means that the chelant forms six bonds with the chelated metalion). Examples of chelants that form such complexes with Cu²⁺ are EDDS,HBED, EDTA and EDDHA. Forming such complexes efficiently prevents thechelated heavy metal ion from reacting with the molecule of theoxidizing agent, for example hydrogen peroxide.

As the table above shows, EDTA has a very good capacity at inhibitingthe red-ox chemistry of copper. This was a very surprising finding forthe inventors because experiments had shown that EDTA had very poordamage prevention properties in “real” conditions of use wherein theconcentration of transition metal ion such as copper and alkaline-earthmetal ion such as Ca²⁺ are high compared to lab-condition wherein thewater is de-ionized for experiments. (see EXPERIMENTALS hereinbelow).The Applicant believes that this clearly shows that the ratio$\frac{\log\quad K_{CuL}}{\log\quad K_{CaL}}$at pH 10 is an essential parameter to use in order to determine theoxidative damage prevention efficiency of chelants in real conditions ofuse.

Without being bound by theory, it is believed that chelants act tochelate environmental and intrinsic heavy metal ions such as iron,manganese and copper. In the absence of chelants, these heavy metal ionsreact with hydrogen peroxide to give highly damaging species such asfree radicals, which are believed to be very harmful to the disulphidebonds of hair. It is believed that alkaline-earth metal ions such asCa²⁺ compete with heavy metal ions to form complexes with the chelants,therefore chelants with a much higher affinity for Cu²⁺ than for Ca²⁺will much more efficiently prevent oxidative damage than chelants with alower relative affinity for Cu²⁺. The Applicant believes that theimportance of measuring damage under real life conditions (i.e. at pH10and with non-deionized water) was never recognized or foreseen untilnow.

Oxidizing Agent

The compositions according to the present invention comprise or are usedin combination with a composition that comprises at least one oxidizingagent. Preferred oxidizing agents for use herein are water-solubleperoxygen oxidizing agents. “Water-soluble” as defined herein means thatin standard condition at least 0.1 g, preferably 1 g, more preferably 10g of said oxidizing agent can be dissolved in 1 liter of deionizedwater. The oxidizing agents are valuable for the initial solubilisationand decolorisation of the melanin (bleaching) and accelerate thepolymerization of the oxidative dye precursors (oxidative dyeing) in thehair shaft.

Preferred water-soluble oxidizing agents are inorganic peroxygenmaterials capable of yielding hydrogen peroxide in an aqueous solution.Water-soluble peroxygen oxidizing agents are well known in the art andinclude hydrogen peroxide, inorganic alkali metal peroxides such assodium periodate and sodium peroxide and organic peroxides such as ureaperoxide, melamine peroxide, and inorganic perhydrate salt bleachingcompounds, such as the alkali metal salts of perborates, percarbonates,perphosphates, persilicates, persulphates and the like. These inorganicperhydrate salts may be incorporated as monohydrates, tetrahydrates etc.Mixtures of two or more such oxidizing agents can be used if desired.Preferred for use in the compositions according to the present inventionis hydrogen peroxide.

In conventional dyeing and bleaching compositions, levels of peroxygenoxidizing agent are usually of from about 0.1% to about 7% by weight.Higher levels, whilst giving good results in term of efficacy were untilnow not practical because of increased hair damage. The oxidative damageprotection provided by the present invention makes it now possible touse oxidizing agent such as hydrogen peroxide in level up to 40% in theoxidizing composition. However, for safety reasons, level above 12%should be carefully investigated before being used on human. Preferably,the level of the oxidizing agent in the oxidizing composition is of fromabout 0.5% to about 20% by weight, more preferably of from about 1% toabout 15%. The compositions according to the present invention provideexcellent gray coverage, vibrant colors and acceptable damage at levelabove about 7% (typically about 12%).

The weight ratio of oxidizing agent to oxidative damage inhibitingchelant (e.g. EDDS) is preferably in the range of from 50:1 to 1:50,preferably from 25:1 to 1:25, more preferably from 15:1 to 1:15, evenmore preferably of from 9:1 to 1:10.

Additional Components

Moreover, it is also intended that the compositions of the presentinvention may be complex compositions, which in addition to the chelantand oxidizing agent comprise other components that may or may not beactive ingredients. This includes, but is not limited to, bufferingagents, hair dyeing agents such as oxidative dye precursors,non-oxidative dyes, thickeners, solvents, enzymes, anionic, non ionic,amphoteric and cationic surfactants, conditioning agents, carriers,antioxidants, stabilizers, perming actives, perfume, hair swellingagents and/or polymers. Some of these additional components are detailedhereafter.

It is preferred, however, that the composition according to the presentinvention should preferably be substantially free from sodiumnonanoylbenzenesulfonate (NOBS), acetyltriethylcitrate (ATC), sodium(6-nonaamidocaproyl)oxybenzenesulfonate, peracetic and pernanoic acidsince they have a negative effect on the efficiency of bleaching andcoloring and increase damage at a pH above 8. The composition should besubstantially free from organic peroxyacid precursors and preformedorganic peroxyacid, such as those defined in WO97/24106. The termsubstantially free as used herein means that the compositions accordingto the present invention should comprise less than 1.5%, preferably lessthan 1%, more preferably less than 0.5%, even more preferably less than0.1%, still more preferably 0% by weight of the composition of suchcompounds.

It is might be also preferred that the compositions of the presentinvention are substantially free of inorganic phosphate or phosphonatecompounds since they are usually non- or poorly biodegradable.

Finally, the compositions according to the present invention can beprovided in any usual form, such as for example an aqueous composition,a powder, a gel or an oil-in-water emulsion. Preferred media for thecompositions according to the present invention are thickened solutionscomprising a salt-tolerant thickener or oil-in-water emulsions.

pH Buffering Agents

The compositions according to the present invention preferably furthercomprise a pH buffering agent. The pH of the composition is preferablyof from about 8 to about 12, more preferably of from about 9 to about11, even more preferably of from about 9.5 to about 10.5. Suitablebuffering agents are well known in the art and include for exampleammonia/ammonium acetate mixture and monoethanolamine (MEA).

Oxidative Hair Dye Precursors

These compounds are well known in the art, and include aromaticdiamines, aminophenols and their derivatives (a representative but notexhaustive list of oxidation dye precursor can be found in Sagarin,“Cosmetic Science and Technology”, “Interscience, Special Edn. Vol. 2pages 308 to 310). Precursors can be used with couplers. Couplers aregenerally colorless molecules that can form colors in the presence ofactivated precursors.

The choice of precursors and couplers will be determined by the color,shade and intensity of coloration that is desired. The precursors andcouplers can be used herein, singly or in combination, to provide dyeshaving a variety of shades ranging from ash blonde to black.

Hair dye compositions will generally comprise from about 0.001% to about10%, preferably from about 0.1% to about 2%, of oxidative dye precursorsand couplers.

Thickeners

The composition of the present invention may optionally further compriseat least about 0.1% of thickeners. Thickeners are preferably comprisedin amount sufficient to provide the composition with a viscosity of fromabout 1 Pa.s to 10 Pa.s (1,000 to 10,000 cP) at 26° C. in order toprovide a composition that can be readily applied to the hair withoutdripping.

Preferred for use herein are salt tolerant thickeners. Salt-tolerantthickeners are functionally defined herein as compounds that increasesthe viscosity of an aqueous composition consisting of 3.8% DTPMP(tetrasodium salt) and 1.95% NH₃ to at least 1 Pa.s (1,000 cP) whenincorporated at levels of 2% by weight as measured at 26.7° C. Theviscosity can be measured with a Brookfield viscometer DVII, using S41spindles for samples under 10 Pa.s (10,000 cP) and spindle S52 forsamples over 10 Pa.s (10,000 cP) (available from Brookfield), with aspeed rating of 1 revolution per minute and samples sizes of 2 ml (forS41 spindle) or 0.5 ml (for S52 spindle).

A non exclusive list of suitable salt tolerant thickeners for use hereininclude xanthan, guar, hydroxypropyl guar, scleroglucan, methylcellulose, ethyl cellulose (commercially available as Aquacote®),hydroxyethyl cellulose (Natrosol®), carboxymethyl cellulose,hydroxypropylmethyl cellulose, microcrystalline cellulose,hydroxybutylmethyl cellulose, hydroxypropyl cellulose (Klucel®),hydroxyethyl ethyl cellulose, cetyl hydroxyethyl cellulose (Natrosol®Plus 330), N-vinylpyrollidone (Povidoneg), Acrylates/Ceteth-20 ItaconateCopolymer (Structure® 3001), hydroxypropyl starch phosphate (Structure®ZEA), polyethoxylated urethanes or polycarbamyl polyglycol ester (e.g.PEG-150/Decyl/SMDI copolymer=Aculyn® 44, PEG-150/Stearyl/SMDIcopolymer=Aculyn 46®), trihydroxystearin (Thixcin®) acrylates copolymer(e.g. Aculyn® 33) or hydrophobically modified acrylate copolymers (e.g.Acrylates/Steareth-20 Methacrylate Copolymer=Aculyn® 22).

Fatty alcohols have thickening properties and can be used in thecompositions of the present invention. Fatty alcohols are however notsalt-tolerant thickeners according to the above definition. A mixture of2% cetyl and stearyl alcohol has for example a viscosity of less thanabout 0.7 Pa.s (700 cP) as measured at 26° C. with a Brookfieldviscometer in the conditions disclosed hereabove.

Conditioning Agent

The compositions of the present invention preferably, but notnecessarily, further comprises at least one conditioning agent.Preferred conditioning agents are selected from silicone materials,especially nonvolatile silicone and amino functionalised silicones,cationic surfactants, cationic polymers and mixtures thereof.

The conditioning agent will generally be used at levels of from about0.05% to about 20% by weight of the composition, preferably of fromabout 0.1% to about 15%, more preferably of from about 0.2% to about10%, even more preferably of from about 0.2% to about 2%. The minimumlevel that is used in a particular composition should be effective toprovide a conditioning benefit. The maximum level that can be used isnot limited by theory, but rather by practicality. It is generallyunnecessary and expensive to use levels in excess of about 10% and,depending on the type of agent (polymeric conditioners being mostprone), such high levels can cause an undesirable weighting down of thehair.

Suitable conditioning agents are disclosed in WO9804237 p. 22-p. 29, andin WO9632919 p. 17-22 both incorporated herein by reference.

EXPERIMENTALS

All results discussed herein were obtained by testing chelants accordingto the following protocols. The chelants tested can be obtained from anyusual supplier.

Hydrogen Peroxide Decomposition Ratio Measurement Protocol

The Hydrogen Peroxide Decomposition Ratio Measurement Protocol isdefined as follows: 6.0% by weight of concentrated ammonium hydroxide(30% active ammonia) is added to deionised water and the pH of thesolution is adjusted to 10 using acetic acid. 300 ppm of copper sulphateand 0.026M of the chelant to be tested are added to said composition. 10ml of this solution is then mixed with 1 ml of hydrogen peroxide (35%active). The initial level of hydrogen peroxide is measured at thismoment (t=0); the final level of hydrogen peroxide is measured after 30minutes. The value of the ratio of the hydrogen peroxide concentrationat t=0 and at t=30 mn is the Hydrogen Peroxide Decomposition Ratio (%Loss).

The initial and final level of hydrogen peroxide can be measuredaccording to any standard technique. The following is a well-known andstandard technique that was used by the inventors: 0.2-0.3 g (the exactquantity being precisely measured) of the solution to be titrated isadded to 40 ml of 10% acetic acid. The autotitrator (Mettler DL58Autotitrator) adds 20 ml of potassium iodide solution (15% in water), 5ml of ammonium molybdate solution (2% in water) and titrates (whilestirring) with 0.1M sodium thiosulphate solution. The level of hydrogenperoxide (% Peroxide) is then calculated from the following equation:${\%{\quad\quad}{Peroxide}} = \frac{{end}\text{-}{{point}\left( {{in}\quad{ml}} \right)} \times {molarity}\quad{of}\quad{sodium}\quad{thiosulphate} \times 34.02}{2 \times 10 \times {sample}\quad{{weight}\left( {{in}\quad g} \right)}}$34.02 being the molecular weight of Hydrogen Peroxide.

Three replicate runs are made at both t=0 and t=30 mn and then averagedto calculate the Hydrogen Peroxide Decomposition Ratio (% Loss).

Chelants having a Hydrogen Peroxide Decomposition Ratio (% Loss) of lessthan 10% are preferred for use herein. Preferably the value of theHydrogen Peroxide Decomposition Ratio is less than 3.5%, more preferablyless than 3%, even more preferably less than 2.0%.

Oxidative Hair Treatment Protocol

For each chelant tested, seven switches of virgin dark hair were used.“Virgin hair” means hair that has never been treated chemically and canbe bought, for example, at Hugo Royer International Ltd, 10 LakesideBusiness Park, Swan Park, Sandhurst, Berkshire, GU47 9ND. The switchesusually weighed about 1.5 g each and are treated stepwise according tothe following protocol.

A bleaching composition comprising the chelant to be tested is preparedby mixing in equal weight amounts a hydrogen peroxide emulsion base andan alkaline (high pH) emulsion base.

The hydrogen peroxide emulsion base contains:

a) 35% by weight of an emulsion base premix comprising 10% stearylalcohol and 5% cetereth 25;

b) 25% of an stabilizing solution comprising 1% tetrasodium DTPA, 0.4%HEDP, 1% sodium hydroxide (32% purity) and water q.s.p

c) 14% of water;

d) 26% of a solution of hydrogen peroxide (35% purity).

The alkaline emulsion base contains:

a) 0.2% by weight of sodium sulphite;

b) 0.2% of ascorbic acid;

c) 3% of ammonium acetate;

d) 44.5% of the same emulsion base premix used for the hydrogen peroxideemulsion base;

e) 11% of an ammonia solution (30% purity) to set the pH toapproximately 10;

f) the amount to be tested of chelant or mixtures of chelants (forexample 3.8% by weight of the alkaline emulsion base of EDDS, equivalentto 1.9% EDDS “on head”);

g) q.s. of water.

The pH of the mixture is buffered to 10 by the alkaline emulsion base.

2 g Of the bleaching composition per g of hair to be treated was appliedon the hair switches and massaged in thoroughly. The hair switches werethen wrapped in a plastic film and put in an oven at 30° C. After 30 mn,they were removed from the oven and from the wrapping film and rinsedfor 1 mn in water. 0.1 g of shampoo per g. of hair was then added andmilked for 30 s at a rate of at least 150 strokes a minute beforerinsing for 30 s. The combined concentration of calcium and magnesiumions (water hardness) of the water used during all experiments (exceptfor the preparation of the compositions tested, wherein water wasdistilled or dionised) was carefully kept at 9 grains per gallon (153ppm), with a molar ratio of Ca²⁺/Mg²⁺ equal to 3:1. The concentration ofcopper (Cu²⁺) ions was kept at about 1 ppm (+/−10%), the exactconcentrations being measured by a standard analytic method. The rinsingwater flow was adjusted to 6 liters per minute). The same shampooing andrinsing process was repeated another time (this is the “Oxidative HairTreatment Protocol With 2 Intermediate Washes” referred to in theclaims) or 9 additional times (this is the “Oxidative Hair TreatmentProtocol With 10 Intermediate Washes” referred to in the claims)depending on the Damage Assessment Protocol used. The excess water wasthen squeezed out of the hair, and the hair dried with a fan. Anystandard shampoo can be used in this protocol as long as it is free fromtransition metal ions such as copper ion and that the level chelants isless than 0.1% by weight of the shampoo. Prell® shampoo was using duringthese tests.

This Oxidative Hair Treatment Protocol can be repeated several times.When damage is measured according to the FT-IR Damage Assessing Protocolor to the Goniophotometer Damage Assessing Protocol (both describedbelow) the Oxidative Hair Treatment Protocol is preferably repeated 5times. This process is described as a 5-Cycle Oxidative Hair TreatmentProtocol With 2 or 10 Intermediate Washes.

Damage Assessing Protocols

Two different test methods were used to assess the protection conferredto hair by the compositions according to the present invention. Thesemethods (FT-IR and Goniophotometer Damage Assessing Protocol) aredescribed in details below.

FT-IR Damage Assessing Protocol

Damage caused to the hair was assessed by the FT-IR (Fourier TransformInfrared) method, which has been established to be suitable for studyingthe effects of oxidative treatments on hair (Strassburger, J., J. Soc.Cosmet. Chem., 36, 61-74 (1985); Joy, M. & Lewis, D. M., Int. J. Cosmet.Sci., 13, 249-261 (1991); Signori, V. & Lewis, D. M., Int. J. Cosmet.Sci., 19, 1-13 (1997)). In particular, these authors have shown that themethod is suitable for quantifying the amount of cysteic acid that isproduced from the oxidation of cystine. In general, the oxidation ofcystine is thought to be a suitable marker by which to monitor theoverall oxidation of the keratinous part of the fiber.

Net, the measurement of cysteic acid units by FT-IR is commonly used tostudy the effects of oxidative treatments or environmental oxidationupon keratin protein containing fibers such as hair and wool.

Signori & Lewis (D. M., Int. J. Cosmet. Sci., 19, 1-13 (1997)) haveshown that FT-IR using a diamond Attenuated Total Internal Reflection(ATR) cell is a sensitive and reproducible way of measuring the cysteicacid content of single fibers and bundles. They have shown that thistechnique is more suitable than using the FT-IR method in simpletransmission or microscope modes. They have also shown that the diamondcell ATR was significantly more sensitive and reproducible than the ZnSEcell. Hence, the method that we have employed to measure the cysteicacid content of multiple fiber bundles and full hair switches, is basedupon the FTIR diamond cell ATR method employed by Signori and Lewis(1997). The detailed description of the method used for testing thedifferent damage inhibitors follows thereafter:

A Perkin Elmer Spectrum® 1 Fourier Transform Infrared (FTIR) systemequipped with a diamond Attenuated Total Internal Reflection (ATR) cellwas used to measure the cysteic acid concentration in human hair. Inthis method, hair switches of various sizes and colours can be used. Theswitches were platted (˜1 plait per cm) in order to minimize variationsin surface area of contact between readings. The Oxidative HairTreatment Protocol described above was repeated for 5 cycles to mimicthe behavior of hair after repeated bleaching cycles. Following thistreatment, four readings per switch were taken (˜⅓ and ⅔ s down theswitch on both sides), and an average calculated. Backgrounds werecollected every 4 readings, and an ATR cell pressure of 1N/m wasemployed. The cell was cleaned with ethanol between each reading, and acontamination check performed using the monitor ratio mode of theinstrument. As prescribed by Signori & Lewis in 1997, a normalizeddouble derivative analysis routine was used. The original spectra wereinitially converted to absorbance, before being normalized to the 1450cm⁻¹ band (the characteristic and invariant protein CH₂ stretch). Thisnormalized absorbance was then twice derivatised using a 13 pointaveraging. The value of the 1450 cm⁻¹ normalized 2^(nd) derivative ofthe absorbance at 1040 cm⁻¹ was taken as the relative concentration ofcysteic acid. This figure was multiplied by −1×10⁻⁴ to recast it intosuitable units. It was found that virgin human hair produced a value of˜20 cysteic acid units, and heavily oxidized hair produced valuesof >170. The following instrumental conditions were employed: SpectralResolution - 4 cm⁻¹ Data Interval - 0.7 cm⁻¹ Mirror Scan Speed - 0.2cms⁻¹ Number of Background Scans - 20 Number of Sample Scans - 20 ScanRange - 4000 cm⁻¹ to 600 cm⁻¹

Using these instrumental conditions and the 2nd derivative analysisroutine, it was found that the sensitivity and reproducibility of themethod in the range 10 to 150 cysteic acid units, are both ˜±5-10%.

Goniophotometer Damage Assessing Protocol

Damage caused to the hair was also assessed by the Goniophotometermethod, which has been established to be suitable for studying theeffects of changes in surface condition of the hair (R. F. Stamm, M. L.Garcia and J. J. Fuchs, ‘The Optical Properties of Human Hair-I.Fundamental Consideration and Goniophotometer Curves’, and ‘II. TheLustre of Human Hair Fibres’, J Soc. Cosmet. Chem. 28, 571-599 and601-609 (September 1977)). It has been demonstrated that the shine(gloss or lustre) is proportional to the relative amounts of specularlyand diffusely reflected light (I_(s) and I_(d) respectively). This isdictated by the refractive index of the fibre and the roughness of thesurface. By coating the hair fibres in a very fine coating of goldbefore measuring the reflected light the internal reflection of thefibre is eliminated and the shine can be used as a sensitive measure ofthe roughness of the surface. For example, a smooth surface will reflectlight that has a large specular content and a small diffuse content

A GP200 Goniophotometer was used from Murakami Colour ResearchLaboratory. The gold coating was applied using an Emitech K-500 sputtercoater.

Randomly chosen single fibres were loaded onto a single fibre holder (10fibres per holder) and held in a parallel array. A minimum of 12 holderswere loaded giving good reproducibility of +/−4%. Each single fibreholder was coated in gold using the Emitech sputter coater for 1 minutewith a 25 mA coating rate. This gives a coating of between 10-300 nm ofgold on the surface. The sample holder was then loaded into the GP200Goniophotometer. The following instrumental conditions were employed:

Reflection measurement mode—fixed incident angle, variable receivingangle

Incidence Angle=+30

Detector Angle range=−30 to +60

Light aperture values: Incident=4.0; Receiving=2.0

Inclination of speciman table=0 deg

Sensitivity=850

High voltage of photomultiplier=725

For each set of fibres a reflectance spectrum is obtained. From thisspectrum the reflectance peak maximum (Imax) is normalised to 1 and allthe other reflectances are scaled according to this maximumI(norm)=I/Imax

Where I(norm)=normalised intensity, I=reflectance intensity,Imax=reflectance peak maximum.

The shine is calculated from the difference between the specularreflection and diffuse reflection at 0° divided by the width of thespecular peak at its half maximum (in angular units)S(norm)=[(1−I(0))/σ]*100

Where S(norm)=normalised shine, I(0)=normalised reflectance at 0°,σ=angular full width at half maximum in °.

Comparative Tests

Damages Measured According to the FTIR-IR Damage Assessing Protocol

The following illustrates the effect of EDDS and 4 other chelants:ethylenediaminetetraacetic acid (EDTA), 1-hydroxyethane-1,1-diphosphonicacid (HEDP), diethylenetriaminepentaacetate (DTPA) anddiethylenetriamine-N,N,N′,N″,N″-penta(methylene phosphonate) (DTPMP).The weight percentages for each chelant are indicated in the first lineof the table below. The tri-sodium salt of EDDS, tetra-sodium salt ofEDTA, di-sodium salt of HEDP, penta-sodium salt of DTPA and tetra-sodiumsalt of DTPMP were used.

In this experiment EDDS was tested at 1.9% by weight on head, but EDDSalso provides excellent benefits at much lower concentrations. Damageand lightening effects were assessed after 5 cycles according to theOxidative Hair Treatment Protocol With 2 Intermediates Washes asdescribed above. Human hair is often bleached or dyed 5 times or moreduring its life, which makes this 5 cycle test very meaningful. Theresults are shown in the table below: Weight % (“on-head”) 1.9% 2.0%2.0% 2.65% 3.8% EDDS EDTA HEDP DTPA DTPMP Damage after 5 cycles 110 165163 147 142 (cysteic acid units) Damage benefit vs +33% —  +1% +11% +14%EDTA 2%

Hair treated with 1.9% by weight EDDS displayed much less damage thanhair treated with any other chelant. However increasing the level of anychelants allows reducing oxidative damage to value below 160 cysteicacid units. The value for damage without any added chelant is about 170damaged cysteic units. The lightening effect of the oxidativecomposition was of about the same quality for all compositions.

Damages Measured by the Goniophotometer Damage Assessing Protocol

The following illustrates the effect of EDDS, HPPDS and 4 otherschelants: EDTA, HEDP, DTPA and DTPMP. The tri-sodium salt of EDDS,tetra-sodium salt of HPPDS, tetra-sodium salt of EDTA, di-sodium salt ofHEDP, penta-sodium salt of DTPA and tetra-sodium salt 10 of DTPMP wereused. The corresponding weight percentage is indicated in the first lineof the table below. Damage was assessed after 5 cycles according to theOxidative Hair Treatment Protocol With 10 Intermediate Washes describedabove (at least 11 measures for each chelant were made and averaged togive the values compiled below).

The normalized shine can slightly vary depending on the type of virginhair used as 15 starting material. In order to obtain data that areindependent of the starting material, the normalized shine valuesobtained as described above have been subsequently divided by the valueobtained for virgin (untreated) hair. Weight % 0.95% 0.97% 1.0% 1.0%1.32% 1.90% EDDS HPPDS EDTA HEDP DTPA DTPMP Normalized 1.03 1.00 0.7040.730 0.757 0.92 shine ratio (hair treated after 9 cycles/ virgin hair)

EXAMPLES

The following examples illustrate oxidative dye compositions accordingto the present invention and methods of manufacture thereof. It isunderstood that the examples and embodiments described herein are forillustrative purposes only and that various modifications or changes inlight thereof will be suggested to one skilled in the art withoutdeparting from the scope of the present invention. Examples offormulation: emulsion 1 2 3 4 5 6 7 8 9 10 Sodium sulphite 0.1 0.1 0.10.1 0.1 0.1 0.1 0.1 0.1 0.1 Ascorbic Acid 0.1 0.1 0.1 0.1 0.1 0.1 0.10.1 0.1 0.1 Ammonium Acetate 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5Ammonia (30% active) 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 Ceteareth25 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cetyl Alcohol 1.6 1.6 1.6 1.61.6 1.6 1.6 1.6 1.6 1.6 Stearyl Alcohol 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.33.3 3.3 Sodium Benzoate 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1Phenoxyethanol 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 DTPMP(tetrasodium salt of) 2.5 — 2.5 — — 1.0 — 1.0 0.5 3.0 DTPA (pentasodiumsalt of) — — 0.5 1.0 — — 0.5 — 0.5 — EDDS (trisodium salt of) — 1.0 —1.0 0.5 1.0 1.0 1.0 0.5 — Para-phenylene diamin 0.8 0.5 0.6 0.5 0.8 0.80.5 0.6 0.5 0.8 Para-aminophenol 0.2 0.3 0.2 0.1 0.2 0.2 0.3 0.2 0.1 0.2Meta-aminophenol 1.0 0.5 1.0 0.6 1.0 1.0 0.5 1.0 0.6 1.0 Resorcinol 1.61.2 1.6 0.8 1.6 1.6 1.2 1.6 0.8 1.6 Hydrogen Peroxide (35% active) 8.68.6 8.6 12.9 17 17 17 34 34 34 Trimethylsilylamodimethicone 0.5 0.5 1.52.0 2.0 2.0 2.0 2.0 2.0 2.0 (SF1708) Polyquaternium 10 (Polymer JR30M)0.2 0.2 — 0.2 0.2 0.2 0.2 — — Xanthan gum 0.5 0.5 — 1.0 0.5 0.5 0.5 0.50.5 1.0 Cetyl hydroxyethyl — — 0.8 1.0 0.8 0.5 0.5 0.5 0.5 1.0 Cellulose(Natrosol 330CS Plus) pH adjust to pH 10 qs qs qs qs qs qs qs qs qs qsWater qs qs qs qs qs qs qs qs qs qs

Examples of formulation: thickened aqueous solution 1 2 3 4 5 6 7 8 9 10Sodium sulphite 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Ascorbic Acid0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Citric Acid 1.0 1.0 1.0 1.0 1.01.0 1.0 1.0 1.0 1.0 Ammonia (30% active) 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.06.0 6.0 Acrylates Copolymer (Aculyn ® 33A) 2.4 2.4 2.4 2.4 2.4 2.4 2.42.4 2.4 2.4 Oleth 10 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Oleth 2 0.80.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Oleic Acid 0.9 0.9 0.9 0.9 0.9 0.90.9 0.9 0.9 0.9 Cocamide DEA 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0DTPMP (tetrasodium salt of) 2.5 — 2.5 — — 1.0 — 1.0 0.5 3.0 DEPTA(pentasodium salt of) — — 0.5 1.0 — — 0.5 — 0.5 — EDDS (trisodium saltof) — 1.0 — 1.0 0.5 1.0 1.0 1.0 0.5 — Para-phenylene diamine 0.8 0.5 0.60.5 0.8 0.8 0.5 0.6 0.5 0.8 Para-aminophenol 0.2 0.3 0.2 0.1 0.2 0.2 0.30.2 0.1 0.2 Meta-aminophenol 1.0 0.5 1.0 0.6 1.0 1.0 0.5 1.0 0.6 1.0Resorcinol 1.6 1.2 1.6 0.8 1.6 1.6 1.2 1.6 0.8 1.6 Hydrogen Peroxide(35% active) 8.6 8.6 8.6 13 17 17 17 34 34 34 Behentrimonium Chloride0.5 0.5 1.5 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Dicetyldimonium Chloride 0.2 0.20.7 0.2 0.2 0.2 0.2 — — — Acrylates Steareth-20 0.5 0.5 — 1.0 0.5 0.50.5 0.5 0.5 1.0 Methacrylate Copolymer (Aculyn ® 22) Propylene Glycol8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 Ethoxy Diglycol 4.2 4.2 4.2 4.24.2 4.2 4.2 4.2 4.2 4.2 pH adjust to pH 10 qs qs qs qs qs qs qs qs qs qsWater qs qs qs qs qs qs qs qs qs qs

The above compositions are useful for dyeing hair with reduced damage.Similar compositions not including oxidative dye precursors and couplers(in the above examples para-aminophenol, meta-aminophenol andresorcinol) can be used for bleaching (lightening) hair.

Oxidative hair dye compositions are usually sold in kits comprising, inseparate containers, a dye component (also called “dye cream” foremulsion or “dye liquid” for solution) comprising the oxidative dyeprecursors (and usually the Hair Swelling Agent) and a hydrogen peroxidecomponent (also called “hydrogen peroxide cream” for emulsion or“hydrogen peroxide liquid” for solution) comprising the oxidizing agent(usually hydrogen peroxide). The consumer mixes the dye component andhydrogen peroxide component immediately before use. The examples of thetables above illustrate the resulting mixtures.

Similarly, bleaching compositions are usually sold as a kit comprisingtwo or three separate containers. The first contains the hair-swellingagent (e.g. ammonia), the second contains the oxidizing agent and thethird (optional) contains a second oxidizing agent (e.g. alkali orammonium salt of persulphates, percarbonate, perborate). The bleachingcompositions are obtained by mixing the above-mentioned compositionsimmediately before use.

These kits are well known in the art and the composition in eachcontainer can be manufactured utilizing any one of the standardapproaches, these include:

-   Oil in water process-   Phase Inversion process-   One-pot process

The chelants are usually added to a proportion of the water at the startof the making process at ambient temperature, and allowed to dissolve.The fatty components are then added and the mixture is processed as isnormal for the above outlined procedures. For example, in a 1 potprocess the polymers and chelants would be predissolved in water, thefatty materials added and then the whole heated to about 70-80° C.

A controlled cooling and optional shearing process to form the finalstructured product in the case of an emulsion would then follow.Addition of the ammonia and pH trimming complete the making process ofthe dye cream.

In the case of a liquid solution comprising acrylate polymers, thesewould be formulated into the hydrogen peroxide component. The glycolsolvents and fatty components are formulated into the dye component. Astructured product is formed when the dye and hydrogen peroxidecomponents are mixed together prior to use of the composition, throughdeprotonation of the polymer acrylic acid groups yielding a polymericmicro-gel. Further details on the manufacture of these two-part aqueouscomposition for coloring hair, which forms a gel on mixing of the twoparts can be found in U.S. Pat. No. 5,376,146, Casperson et al. and U.S.Pat. No. 5,393,305, Cohen et al.

The composition of the present invention can also be formulated as2-part aqueous compositions comprising polyetherpolyurethane asthickening agent (such as Aculyn® 46) as described in U.S. Pat. No.6,156,076, Casperson et al. and U.S. Pat. No. 6,106,578, Jones.

When the compositions of different containers are mixed before use andthe resulting mixture comprises the chelants claimed, there is nopreference on how the chelants are distributed in these containers.Obviously chelants that can be altered by hydrogen peroxide (or anyoxidizing agent used) such as secondary amine chelants should however beformulated in the dye component. The hydrogen peroxide component shouldhowever preferably comprise at least about 0.1% of a stable chelant tostabilize hydrogen peroxide. This stabilizer is required to prevent thehydrogen peroxide from decomposing too rapidly. For example EDTA can beused in the hydrogen peroxide component as stabilizer.

Methods of Use

It is understood that the examples of methods of use and embodimentsdescribed herein are for illustrative purposes only and that variousmodifications or changes in light thereof will be suggested to oneskilled in the art without departing from the scope of the presentinvention.

Without Pretreatment

The chelants according to the present invention are preferablyformulated directly in the oxidizing compositions applied on hair (e.g.oxidative dye compositions or bleaches).

Oxidative Dye

Oxidative dye compositions are usually sold as a kit comprising at leasttwo separate containers: one contains the oxidative dye precursors withthe hair-swelling agent (e.g. ammonia) in a suitable carrier (e.g. dyecream or liquid) and the other contains the oxidizing agent in asuitable carrier (e.g. hydrogen peroxide cream or liquid). The consumerprepares the oxidative dye composition immediately before use by mixingboth compositions and applies it on hair. After working the mixture afew minutes (to insure uniform application to all of the hair), theoxidative dye composition is allowed to remain on the hair for an amountsufficient for the dyeing to take place (usually about 30 minutes). Theconsumer then rinses his/her hair thoroughly with tap water and allowsit to dry. It is observed that the hair has changed from its originalcolor to the desired color.

When present, the optional conditioning agent can be packaged partly orin totality in a third container. In this case, all three compositionscan be mixed immediately before use and applied together, or the contentof the third container can be applied (after an optional rinse step) asa post-treatment immediately after the oxidative dye compositionresulting from the mixture of the other containers.

Bleaching Compositions

Bleaching compositions are usually sold as a kit comprising two or threeseparate containers. The first contains the hair-swelling agent (e.g.ammonia), the second contains the oxidizing agent and the third(optional) contains a second oxidizing agent (e.g. alkali or ammoniumsalt of persulphates, percarbonate, perborate). The consumer preparesthe bleaching compositions immediately before use by mixing allcompositions and applies the mixture on hair (as for the oxidative dyecomposition) for an amount of time sufficient for the bleaching to takeplace (usually about 30 mn).

In this kind of kit comprising at least two containers there is nopreference on the distribution of the chelants and conditioners in thecontainers, although it is preferred that the composition comprising theoxidizing agent comprises at least a small amount of chelant (which isnot necessary a phosphonate chelant) to stabilize the oxidizing agent.

As for oxidative dye compositions, the optional conditioning agent canbe packaged partly or in totality in a third container. In this case,all three compositions can be mixed immediately before use and appliedtogether, or the content of the third container can be applied (after anoptional rinse step) as a post-treatment immediately after the oxidativedye composition resulting from the mixture of the other containers.

With Pretreatment

The chelants can also be applied to hair as a pre-treatment. Thepretreatment composition (“first composition”) can be appliedimmediately before the oxidizing composition (“second composition”) orafter a longer period of time.

Pretreatment Immediately Followed by an Oxidizing composition

In the case of a pretreatment applied on hair and immediately followedby the oxidizing composition, said pretreatment composition can berinsed off hair before the application of the oxidizing composition, butwill be preferably kept on the hair during the application of theoxidizing compositions, the resulting mixture being rinsed off followingthe oxidizing step. Kits comprising one container for the firstcomposition (pre-treat) and one, two or more containers for the secondcomposition (oxidizing composition) can be advantageously used for thismethod. Two containers or more can be required for the secondcomposition in case this second composition is prepared immediatelybefore use by mixing the content of two containers or more (e.g.oxidative hair dye composition or bleaching composition). The kit canalso comprise an additional container for a composition comprising aconditioning agent that is applied independently from the secondcomposition in a third step, optionally following a rinsing step.

Color Care

The pretreatment can also take place as a “color care” treatment anytimebetween two oxidative treatments but not immediately prior to one. The 2oxidative treatments are preferably separated by at least one day, morepreferably at least one week. Oxidative hair dye treatments aregenerally repeated about once a month and obviously, hair will beusually rinsed with water immediately after each oxidative treatment.The “color care” treatment can be repeated as many times as practicalbetween the two oxidative treatments, which can be once, twice or more.

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is, therefore,intended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. (canceled)
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 8. (canceled)
 9. A composition according toclaim 19, wherein said composition has a pH from about 8 to about 12.10. A composition according to claim 19, wherein said composition is inthe form of an oil-in-water emulsion.
 11. A composition according toclaim 19, wherein said composition is in the form of a thickened aqueoussolution.
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 15. (canceled)16. (canceled)
 17. (canceled)
 18. (canceled)
 19. A composition suitablefor treating hair comprising: a) an oxidizing agent; and b) a chelant(L) having a $\frac{\log\quad K_{CuL}}{\log\quad K_{CaL}}$ ratiocalculated at pH 10 of at least about 3.20, wherein log K_(CuL) is thecommon logarithm of the Conditional Stability Constant of said chelantwith Cu²⁺ and log K_(CaL) is the common logarithm of the ConditionalStability Constant of said chelant with Ca²⁺; wherein said chelant is inan amount sufficient to provide a Normalized Shine Ratio of at leastabout 0.95 as measured by the Goniophotometer Damage Assessing Protocolafter a 5-Cycle Hair Oxidative Treatment Protocol With 10 IntermediateWashes.
 20. (canceled)
 21. A composition according to claim 19, whereinsaid chelant (L) has a Hydrogen Peroxide Decomposition Ratio (% Loss) ofless than about 10% as measured by the Hydrogen Peroxide DecompositionRatio Measurement Protocol.
 22. A composition according to claim 19,wherein said chelant (L) is capable of forming a hexadendate complexwith Cu²⁺.
 23. A composition according to claim 19, wherein said chelant(L) is an aminocarboxylic acid chelant selected from the groupconsisting of diamine-N,N′-dipolyacids, monoaminemonoamide-N,N′-dipolyacids andN,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid (HBED),salts thereof, derivatives thereof and mixtures thereof.
 24. Acomposition according to claim 23, wherein said aminocarboxylic acidchelant comprises at least two acid groups independently selected from acarboxylic acid group (—COOH), a sulphonic group (—SO₃H), ano-hydroxyphenyl group, the m-hydroxyphenyl group, and a p-hydroxyphenylgroup.
 25. A composition according to claim 24, wherein saidaminocarboxylic acid chelant is selected from the group consisting ofethylenediamine-N,N′-disuccinic acid (EDDS),ethylenediamine-N,N′-diglutaric acid (EDDG),2-hydroxypropylenediamine-N,N′-disuccinic acid (HPDDS),glycinamide-N,N′-disuccinic acid (GADS),ethylenediamine-N-N′-bis(ortho-hydroxyphenyl acetic acid) (EDDHA), andsalts thereof, derivatives thereof and mixtures thereof.
 26. Acomposition according to claim 19, wherein said oxidizing agent ispresent at a level of from about 0.1% to about 40% by weight of thecomposition and is selected from water-soluble oxidizing agents andmixtures thereof.
 27. A composition according to claim 19, furthercomprising at least one oxidative hair dye precursor.
 28. A method oftreating hair, said method comprising the steps of: i) applying a firstcomposition comprising an oxidizing agent; ii) applying a secondcomposition comprising a chelant (L) having a$\frac{\log\quad K_{CuL}}{\log\quad K_{CaL}}$ ratio calculated at pH 10of at least about 3.20, wherein log K_(CUL) is the common logarithm ofthe Conditional Stability Constant of said chelant with Cu²⁺ and logK_(CaL) is the common logarithm of the Conditional Stability Constant ofsaid chelant with Ca²⁺; wherein said chelant is in an amount sufficientto provide a Normalized Shine Ratio of at least about 0.95 as measuredby the Goniophotometer Damage Assessing Protocol after a 5-Cycle HairOxidative Treatment Protocol With 10 Intermediate Washes; and iii)applying a third composition comprising a second oxidizing agent; andwherein steps i) and iii) are separated by at least 1 day and step ii)does not take place immediately before step iii).
 29. A kit for dyeinghair comprising a first and a second compositions packaged in differentcontainers, wherein said first composition comprises an oxidizing agentand said second composition comprises an oxidative dye precursor,wherein the resulting mixture of said first and second compositions is acomposition according to claim
 27. 30. A method of dyeing human hair,said method comprising the steps of: i) mixing the first and secondcomposition of a kit according to claim 29; ii) applying the mixtureobtained after step i) to hair; iii) massaging said mixture into hair;iv) retaining said mixture on the hair for an amount of time sufficientfor mixture to dye the hair; iv) rinsing off said composition withwater.
 31. A method of treating hair, said method comprising the stepsof: i) applying to the hair a first composition comprising a chelant (L)having a $\frac{\log\quad K_{CuL}}{\log\quad K_{CaL}}$ ratio calculatedat pH 10 of at least about 3.20, wherein log K_(CuL) is the commonlogarithm of the Conditional Stability Constant of said chelant withCu²⁺ and log K_(CaL) is the common logarithm of the ConditionalStability Constant of said chelant with Ca²⁺; wherein said chelant is inan amount sufficient to provide a Normalized Shine Ratio of at leastabout 0.95 as measured by the Goniophotometer Damage Assessing Protocolafter a 5-Cycle Hair Oxidative Treatment Protocol With 10 IntermediateWashes; and ii) applying to the hair a second composition comprising anoxidizing agent; wherein step i) takes place before step ii).
 32. Amethod of treating hair according to claim 31, wherein step i) takesplace immediately before step ii).
 33. A method of treating hairaccording to claim 31, wherein said first composition is not rinsed offthe hair before said second composition is applied to the hair.
 34. Akit for treating hair comprising: i) a first separately packagedcomposition comprising a chelant (L) having a$\frac{\log\quad K_{CuL}}{\log\quad K_{CaL}}$ ratio calculated at pH 10of at least about 3.20, wherein log K_(CuL) is the common logarithm ofthe Conditional Stability Constant of said chelant with Cu²⁺ and logK_(CaL) is the common logarithm of the Conditional Stability Constant ofsaid chelant with Ca²⁺; wherein said chelant is in an amount sufficientto provide a Normalized Shine Ratio of at least about 0.95 as measuredby the Goniophotometer Damage Assessing Protocol after a 5-Cycle HairOxidative Treatment Protocol With 10 Intermediate Washes; and ii) asecond separately packaged composition comprising an oxidizing agent.